Effects of fluopyram and azadirachtin integration with sunn hemp on nematode communities in zucchini, tomato and sweet potato in Hawaii

• Published in: Journal of nematology Vol. 53; no. 1; pp. 1 - 15
• Main Authors: Waisen, Philip, Wang, Koon-Hui, Uyeda, Jensen, Myers, Roxana Y.
• Format: Journal Article
• Language: English
• Published: Poland Sciendo 01.01.2021; Exeley Inc
• Subjects: Arts & Humanities; Chemigation; Free-living nematodes; Meloidogyne spp; Nematicides; Rotylenchulus reniformis; Soil health; spp; Meloidogyne spp; Chemigation; Nematicides; Free-living nematodes; Rotylenchulus reniformis; Soil health
• ISSN: 0022-300X; 2640-396X; 2640-396X
• DOI: 10.21307/jofnem-2021-030

Fluopyram (Velum One) is a synthetic nematicide and azadirachtin (Molt-X ) is a biological nematicide. Both have shown promise against plant-parasitic nematodes on several agriculturally important crops. There is a lack of information on integration of pre-plant sunn hemp ( ) cover crop with these post-plant nematicides, aiming to improve plant-parasitic nematodes management and mitigate any detrimental effects on free-living nematodes. Three field trials were conducted to investigate the effects of fluopyram alone or in combination with pre-plant sunn hemp cover crop, and azadirachtin combined with pre-plant sunn hemp on and spp., and free-living nematodes. Zucchini ( ) and tomato ( ) were grown in Trials I and II, and sweet potato ( ) only was grown in Trial III. In all three trials, early applications of fluopyram at crop planting were effective in suppressing the abundance of spp. ( and ) but it was not effective in reducing in the soil. Combining sunn hemp with fluopyram was suppressive to on short-term zucchini crop, but not on longer term tomato and sweet potato crops. In addition, application of fluopyram at transplanting was the key to successful suppression of spp. as later fluopyram chemigation (at 2 weeks after planting in Trial II or 1 month after planting in Trial III) had no effect against spp. On the other hand, planting of sunn hemp followed by monthly post-plant azadirachtin application consistently suppressed , but this treatment did not suppress spp. Integrating sunn hemp with fluopyram increased zucchini yield by >2.3 folds and that with azadirachtin increased the zucchini yield by >1.7 folds. Although no yield improvement was observed on tomato in Trial II, integrating sunn hemp with azadirachtin and fluopyram increased tomato yield by 0.23 and 1.12 folds, respectively, in Trial I. Marketable yield of sweet potato was increased by 4.5–6.4 folds in all the fluopyram treatments but was only increased 61.5% by sunn hemp plus azadirachtin treatment. While fluopyram alone often reduced the abundance of free-living nematodes, integrating with sunn hemp mitigated the negative impacts of fluopyram on soil health.